I LOVE my puffers...
I set up a 30 gallon with dwarf puffers - they are SO FUN to watch. They come up to the glass when I put my face up to the tank and stare at me. They'll chase each other, so I recommend a lot of hiding places and plants to block their view. They do "claim" their own places within the tank.
I think it's recommended one puffer per 3 gallons of water - I have 9 in my 30 gallon tank. (I bought all the store had because I felt sorry for them, no gravel, no plants, no hiding places - the tank conditions looked miserable, I felt sorry for them, so bought them all - arg!) I had no ammonia spikes, but they were all 1/2 in long when I got them... They shouldn't get much bigger.
The Bumblebee Gobies are great tank mates... I've heard Otos go well with them too for a clean up crew. I also put three kulhi loaches in, I heard they worked well with puffers, but I haven't seen them since I put them in - I'm assuming they're under the gravel.
The Gobies get the blood worms that hit the gravel, the puffers go after all the floating ones - they eat well... I guess once a day or once every two days should be enough feeding. They will come up and eat the worms out of my hand... I've never seen any eat any of the live plants - they appear to chase and nip each other, but as I stare at them watching me... I see no injury or nipped fins on any of them...
The tank had some live plants with lots of little snails in it when I bought it used, the puffers munched up the snails pretty quickly... I don't think there are any snails left.
Good luck,
Kerby